The present disclosure relates generally to electron collectors, and more particularly to a system and method for collecting backscattered electrons within, for example, a substantially evacuated vessel, such as an x-ray tube.
An x-ray tube generally includes a cathode assembly and an anode assembly disposed within a vacuum vessel. The anode assembly includes an anode. The anode commonly includes a stationary or a rotating target with a target track or impact zone fabricated on an outer surface thereof. The target track or impact zone is generally fabricated from a refractory metal with a high atomic number, such as tungsten or a tungsten alloy. The cathode assembly is positioned at some distance from the anode assembly, and a high voltage differential is maintained therebetween in order to accelerate electrons toward the anode. This high voltage differential generates an electric field having a strength defined as the voltage differential between the anode and cathode divided by the distance therebetween. The cathode assembly emits electrons in the form of an electron beam that are accelerated across the high voltage differential and impact the target track at a focal spot at a high velocity. As the electrons impact the target track, the kinetic energy of the electrons is converted to high-energy electromagnetic radiation, or x-rays. The x-rays are then transmitted through an object and intercepted by a detector that forms an image of the object's internal structure and contents.
Many of the electrons incident on the anode target are backscattered from the anode's target track in random directions and scattered throughout the vacuum vessel to strike internal components of the x-ray tube. As these backscattered electrons impact internal components of the x-ray tube, their kinetic energies are transferred to these internal components in the form of thermal energy or heat. Excess heat generation adversely affects the durability of the x-ray tube. Furthermore, in addition to transferring thermal energy to the x-ray tube's internal components, the impact of backscattered electrons also produces off-focus x-ray radiation that may increase undesirable exposure to x-ray radiation and diminish x-ray image quality.
Therefore, there is a need for a system and method of improving the collection of backscattered electrons in an x-ray tube.